In a situation such as reallocation of a hard disk drive provided for one user to another user, a data center or the like in which a disk array device is in operation, for example, needs to perform a process of completely erasing data in a storage device (hereinafter referred to as “shredding”) from a security standpoint, such as in view of leakage of information.
Regarding the shredding, Patent Document 1, for example, discloses the following approach for enabling a host computer or the like to make quick use of a volume targeted for erasure. In this approach, upon receipt of an erase operation request to erase data stored in a storage unit from the host computer, a storage controller detects a logical storage area that can be allocated but different from a logical storage area allocated to the storage unit. The storage controller then allocates the detected logical storage area to the storage unit, and sends, to the host computer as the request source, notification that the storage unit is accessible. Thereafter, the storage controller performs erasing of the data in the logical storage area corresponding to the storage unit targeted for erasure.